Respiratory System at Rest

Question 1

What is the average breathing frequency?

Answer 1

12 breaths per minute

Question 2

What is the average tidal volume?

Answer 2

500ml

Question 3

What is the average minute ventilation?

Answer 3

6 L/min

Question 4

What role does the diaphragm have in inspiration during rest?

Answer 4

Flattens and contracts, pulling the lungs downwards and increasing the volume of the thoracic cavity

Question 5

What role do the external intercostal muscles have in inspiration during rest?

Answer 5

Contract and pull the ribs upwards and outwards, increasing the volume in the thoracic cavity

Question 6

How does the increase in volume of the thoracic cavity inspire air into the lungs?

Answer 6

Air pressure decreases to that below atmospheric pressure of air in the atmosphere, allowing air to move into the lungs

Question 7

What role does the diaphragm have in expiration during rest?

Answer 7

Relaxes and returns upwards to decrease volume in the thoracic cavity

Question 8

What role do the external intercostal muscles have in expiration during rest?

Answer 8

Relax and move the ribs downwards, decreasing the volume in the thoracic cavity

Question 9

How is the efficiency of alveoli be increased?

Answer 9

• Large number of alveoli= large surface area for diffusion
• The membrane between the alveoli and capillaries is thin which means distance for diffusion is reduced

Question 10

How does gaseous exchange at the muscles take place?

Answer 10

Oxygen leaves haemoglobin by diffusion, travelling down the concentration gradient

Question 11

How is the efficiency of gaseous exchange in the muscles increased?

Answer 11

• Thin capillary walls, meaning a shorted distance for diffusion)
• A high capillary network, increasing the surface area for diffusion